The series will end once Naruto becomes Hokage and settles down with Hinata.
However, background producers and people who worked on the series will not be pleased with ending it there, since it was raking in tons of cash, and will create another series to continue it ..
NARUTO GT!
.. And, Naruto will seal his Fox Demon into his son, who will tour the world collecting techniques and skills from all the numerous countries and villages we have still yet to see.